Production of shaped continuous structures



March 3, 1970 w. MARTIN ETAL 3,499,976

PRODUCTION OF SHAPED CONTINUOUS STRUCTURES Filed June 7, 1967 ar/1111A E II/Ira IIII IVOXI'IIIJ,

mveurons; WOLFGANG MARTIN EDELFRIED HAHN HANS SCHMID FRIEDRICH WENGER United States Patent US. Cl. 264-282 3 Claims ABSTRACT OF THE DISCLOSURE Production of shaped continuous structures by passing the structure through a heating zone and subjecting them to mechanical impulses in a direction transverse to the direction of conveyance and if desired additionally bending them about shaping means. Apparatus for carrying out the process are also described.

This invention relates to a method of preparing shaped continuous structures by subjecting the structures to the action of moving mechanical means. It also relates to apparatus for carrying out the method.

Various methods for the production of shaped continuous structures are already known. Thus for example yam may be crimped by subjecting it to swelling and shrinkage. This method has the disadvantage that the degree of crimpiness obtainable is dependent on the tension of the yarn and is therefore capable of only slight variation. Another disadvantage is that the chemicals used for swelling have to be washed out from the yarn after crimping, and this is expensive and uneconomic.

Among the methods of mechanical bulking of yarns those methods have mainly been adopted in industry in which the yarn is twisted at elevated temperature at high speed. It is necessary to insert twist at the rate of 3000 turns per meter in order to achieve adequate crimpiness. It is a disadvantage that the speed achievable limits the efliciency of the method. Moreover it has been found that as the thickness of the yarn increases it becomes increasingly diflicult to achieve high crimpiness.

Methods are also known in which the yarn is treated in a stuffer box. Yarn having uneven bulk may be obtained in this method because of non-uniformity of temperature within the chamber. In the case of yarn of great thickness a relatively high pressure is required so that felting or other deformating of the yarn may take place and this may be troublesome in the further processmg.

We have now found that shaped continuous structures can be particularly advantageously produced. by the action of mechanically operated means by passing a continuous structure through a heating zone and subjecting it to mechanical impulses transversely to the direction of conveyance.

Continuous structures in accordance with this invention include monofilaments, fiber bundles, bristles, yarns having circular or profiled cross-section and ribbons. The structures may consist of, for example, synthetic thermoplastics, cellulose or cellulose derivatives. Structures of hair, for example wool threads, may also be used. The method is particularly siutable for yarn of thermoplastics, for example polyamides, such as nylon 6 or nylon 6,6, polyester, particularly polyethylene terephthalate, or polyacrylonitrile and polyolefins. Monofilaments, for example of 1 to 20 denier, or yarn for 3,499,076 Patented Mar. 3, 1970 example of two to a few thousand monofilaments, are suitable. Structures may be used which have been subjected to stretching, for example structures which have only stretched to a certain degree, e.g. to 500% of their original length, or unstretched structures.

The structures are conveyed through a heating zone in which they are heated to the temperature required for the mechanical treatment. The heating zone advantageously has a temperature such that the structures are heated to a temperature at which they are capable of deformation. This temperature in the case of crystalline thermoplastics is usually at least 100 C. below the melting point of the crystallites and should not exceed the crystalline melting point. According to a particularly advantageous embodiment of the method, for example nylon 6 yarn is heated to temperatures of from to 190 C., nylon 6,6 to to 240 C. and ethylene glycol terephthalic acid polyesters to 180 to 240 C.

Mechanical impulses are made to act on the structures in accordance with this invention transversely to the direction of conveyance. The impulses may act at angles within the range of from 10 to 160 to the direction of conveyance. In a particularly advantageous method the impulses act at about 90 (90:10) to the direction of conveyance. The impulses may be given in the same direction or in alternating directions. It is particularly advantageous to use a method in which the impulses act in alternating directions. This is most advantageously accomplished by causing a mechanical shaping unit to oscillate in a plane, for example transversely to the direction of conveyance of the structure, the unit acting on the structure in alternating directions.

The density of the mechanical impulses should be high enough for the structure to receive at least four and advantageously at least seven impulses per centimeter of its length. The necessary number of impulses is determined by the speed of conveyance and the number of shaping units.

The strength of the impulse required to achieve a permanent set depends on the thickness of the yarn, the composition of the same, the type of cross-section, the tension of the yarn, the temperature and the type of material. The strength of the impulses for a given structure to be used at the required temperature may be determined by preliminary experiment. q

A method in which the structure is additionally bent around a shaping means is particularly advantageous. The shaping means may be for example the edge of a recess in the shaping unit. The angle of bend may be 10 to 90, preferably 60 to 90, measured from the direction of the moving structure. .The radius of curvature of the bend may be 0.1 to 100 times, preferably 0.8 to 5 times, the original diameter of the structure. Bending may even result in the structure being embossed by the bending means.

Apparatus suitable for carrying out the method in accordance with this invention may comprise a casing having one or more apertures for guiding the yarn, one or more apertures transversely to the apertures for guiding the yarn, and shaping elements movably arranged in the apertures and having orifices in the direction of the apertures for guiding the yarn.

This apparatus, which permits a particularly advantageous treatment of the structure with mechanical impulses, is simple, durable and trouble-free.

A particular embodiment of the apparatus is given by way of example in the drawings in which FIGURE 1 shows in diagrammatic form the way in which the method according to this invention may be carried out. A yarn 1 is drawn off from a spool 2, passed over a guide 3 and two guide rollers 4 and supplied to take-oil rollers 5. The

take-off rollers 5 are arranged so that they convey the yarn 1 through a guide tube 6. After the yarn has left the guide tube 6, it enters a vibration chamber 7 in which it is heated to elevated temperature and permanently crimped by the action of mechanical impulses. The crimped yarn is supplied to a Wind-up means by means of a pneumatic pull-out means 8 having a pipe 9 for supplying air.

The manner of operation of the vibration chamber 7 is illustrated in FIGURE 2. A casing 11 has an opening 12 which extends through the casing. The opening 12 serves to guide the yarn 1. Recesses 13 are cut into the casing 11 perpendicularly to the opening 12 and intersecting the same. Shaping means 14 are located in the recesses 13 so as to be movable therein. The shaping means 14 is U-shaped and has orifices 15 following the same direction as the opening 12 for guiding the yarn 1. The shaping means 14 is capable of horizontal movement in the recesses 13, the direction of movement alternating by 180. In the mid position of the shaping means 14, the orifices 15 are in alignment with the opening 12. It is advantageous for the orifices 15 and the opening 12 to have the same diameter.

The essential part of the apparatus is the vibration chamber 7 in which the filament is heated and mechanically shaped. Although the vibration chamber may consist of a casing in which only one shaping means is movably arranged, in most cases it is advantageous to combine two or more shaping means to form a system which are arranged for parallel movement in a plurality of recesses. The shaping means is advantageously driven by a vibration system. The shaping means 14 may be arranged so that between them and the casing 11 there is a space amounting to one or more times the diameter of the yarn 1. In the position of greatest amplitude, the orifices 15 of the shaping means 14 form a gap with the opening 12 of the casing, said cap having a maximum diameter which is less than the diameter of the yarn 1. It is also possible however for the orifices 15 to be moved completely past openings 12 in both directions, so that the yarn is subjected to mechanical impulses as well as being meohanically shaped or embossed. Sometimes it is advantageous to design the chamber so that two or more openings are provided for reception of two or more filamerits. A number of chambers may also be arranged side by side or one behind another. To decrease the tension in the yarn during traverse of the treatment zone, pull-out means can be dispensed with. In this case it is advantageous to guide the direction of the mechanical impulses so that conveyance of the yarn through the openings is achieved.

Other shaping means, formed for example by a system of wires or cables movable relatively to each other, may be used instead of the vibration chambers.

The method and apparatus of the invention are particularly suitable for crimping yarn whose thickness may vary within a very wide range. Thus for example it is possible to give a permanent set to yarn having particularly great thickness. By varying the frequency of the shaping means and the take-up speed it is possible to vary the degree of crimpiness Within a wide range.

The invention is illustrated by the following example.

EXAMPLE In an apparatus as shown in FIGURE 1 of the drawing 1080 denier nylon 6 yarn (consisting of 72 single capillaries) is taken from a supply package and passed by means of take-off rolls through a guide tube of a vibration chamber. The principle of the vibration chamber is shown in FIGURE 2. The shaping means oscillates about its mid position with a frequency of 100 cycles. The casing of the vibration chamber is kept at a temperature of 156 C. by an electric heating element. The yarn is passed by a, pneumatic pull-out means to a wind-up unit.

The crimp rigidity is used as a measure of the texturing effect and is calculated as follows: Crirnped yarn when loaded at the rate of 0.002 g./ den. elongates to the length I. When loaded with 0.2 g./ den. it elongates by the length L. Crimp rigidity is defined as:

100=Percent L Crimp rigidity of the fibers is 15% after storage in water at C. The yarn has 72 bends in mm. Tenacity is 4.1 g./den. and breaking extension 60%.

We claim:

1. A process for crimping a thermoplastic filamentary or ribbon structure which comprises heating said structure to a temperature wherein they are crimpable, passing the heated structure through a passage in a crimping chamber, said passage being a plurality of aligned holes in interleaved fingers of said crimping chamber, which holes together define said passage, and subjecting said structure as it moves through said passage to axial bending by application thereagainst of mechanical thrust, said mechanical thrust being applied by reciprocating every other finger at an angle transverse to said passage while maintaining the remaining fingers stationary.

2. A process as claimed in claim 1 wherein said mechanical thrust is applied at a rate of at least four thrusts per centimeter of said filamentary or ribbon structure.

3. A process as claimed in claim 1, wherein said filamentary or ribbon structure is a polyamide or a polyester, said structure being heated to said temperature within the range from the crystalline melting point to 100 C. below the crystalline melting point.

References Cited 7 UNITED STATES PATENTS 3,377,673 4/1968 Stoller 28l.2

ROBERT F. WHITE, Primary Examiner R. R. KUCIA, Assistant Examiner US. Cl. X.R. 

